Mobicred are ***********

I paid my account in the 3rd May on the 5,7,9,11,13,15 I sent an email stating I used the wrong reference number they must take one nil off as my number has not got four niks. I received my statement and still nothing was credited. I then sent another four emails before they credited me. I then sent another four emails only to get a phone call to say they are not crediting my account as it only went through after closing the books on the 15th. Whose fault is that. I tried to get them to credit me before by sending emails which were never rep**** to. I want my interest back.